Wind power generator

ABSTRACT

The invention relates to a wind power current generator comprising a bearing ( 2 ), a stator ( 3 ), which is fixed to the bearing ( 2 ), a rotor ( 4 ) that can rotate in relation to the stator ( 3 ), a hub ( 5 ) connected to the rotor ( 4 ) and at least two blades radially extending away from the hub ( 5 ). According to the invention, the stator ( 3 ) and the rotor ( 4 ) are formed by tubular sections that are concentric to one another, on whose opposing surfaces permanent magnets ( 7 ) and windings ( 8 ) are placed, and which extend over the magnets and out from the windings in order to accommodate an antifriction bearing on at least one side.

[0001] The present invention relates to a wind power generator as set forth in the preamble of claim 1.

[0002] As is known from the international application WO 01/29413, so-called multipolar wind power generators A1 exist, in which a wind-driven rotor is associated with a power generator which is mounted for rotation on the upper end of a tower. The rotor is secured to the end of a shaft which is mounted so as to rotate in two bearings. These bearings are in turn accommodated within a casing which includes the stator of the power generator. The rotor itself is comprised of a plurality of spokes bearing the ring to which the electromagnets are affixed which come to lie opposite the windings upon rotation of the rotor, which windings in turn are accommodated within the housing.

[0003] It will be noted that in that application a ring-type generator is described in which the rotor shaft is rotatably supported by bearings extending in a ray-like fashion in the housing. On the other hand, the shaft of the rotor actuated by wind energy also acts itself as a rotor shaft of the generator, which is provided with radially arranged spokes designed to support the ring with the electromagnets.

[0004] It shall be noted that in a generator designed in this manner there is no passageway between the interior of the tower and the interior of the blades extending away from the rotor hub. Therefore, the interior ventilation of the rotor blades and in particular a de-icing effect of the blades themselves is difficult to accomplish. Furthermore, the construction of the wind power generator of the known type is complex with regard to the support of the rotor within the stator body. Also, access to the rotor is difficult due to the support of the rotor shaft itself.

[0005] As opposed to this, in the German patent specification DE 44 02 184 a multipolar synchronous generator for wind power plants with horizontal axes is described in which the generator is formed by one single structural unit comprised of a stator and a rotor, which are connected to one another by a floating support provided within the generator. Further, this single structural unit supports the rotary movement of the rotor and receives the externally introduced forces and torques.

[0006] In the proposed case the structure of the rotor proves to be very complex, since the two surfaces of the rotor and of the stator have to be designed to lie at a considerable distance from the antifriction bearings of the rotor.

[0007] Therefore, it is the object of the present invention to avoid the shortcomings of the conventional wind power generators, and to propose a wind power generator in which a maximum of ventilation possibilities is guaranteed, provided by a large degree of accessibility to the various components of the generator, with a high level of structural stiffness being ensured at the same time.

[0008] This and other objects are accomplished in a wind power generator by the characterizing part of claim 1.

[0009] In a preferred embodiment the hollow and multipolar synchronous generator with permanent magnets has outer windings. In this case, the multipolar and synchronous gearless generator with permanent magnets provides for a tubular element which serves simultaneously as a shaft to accommodate the bearings and as a structure for anchoring magnet bodies. In this manner the spokes between the shaft and the ring bearing the permanent magnets are avoided.

[0010] The generator is the integrating component of the supporting structure, and the loads are transferred directly from the hub onto the rotor shaft of the generator, which introduces them into the stator body by way of two bearings disposed at the beginning and at the end of the electrical machine.

[0011] The resultant hollow structure permits access to the front portion of the nacelle, which facilitates maintenance and repair work on the other subsystems. Furthermore, the system makes it possible to mount the hub from the inside.

[0012] The hollow structure further makes it possible for the heat given off by the power electronics housed in the tower and the proportion of heat released by the generator itself to be exploited to guide warm air into the hub and from there into the rotor blades. In this manner a particularly efficient de-icing system is created. No external energy needs to be supplied during operation to heat the rotor blades. Thus, the heat given off by the generator and by the power electronics themselves is put to use in a simple fashion.

[0013] The hollow structure of the generator, inserted into that of the rest of the nacelle, permits the accommodation of the electrical and electronic subsystems inside the nacelle. This results in an excellent protection from lightning on the basis of the principle of the Faraday cage.

[0014] In one variant the hollow and multipolar synchronous generator with permanent magnets has interior windings. By reversing the concept of the preferred embodiment it becomes possible to provide a machine having the stator unit on the inside and the rotor on the outside. The magnets are attached to the inner surface of the rotor and the windings to the outer surface of the rotor shaft.

[0015] The advantages of such a solution are a greater specific output, the possibility of using the total heat released by the generator for the de-icing system, and a simplification of the positioning of the power cables required to conduct the electric current from the generator to the tower.

[0016] In a further variant the tubular section of the stator extends bell-like in the direction of the hub and has a bell head with a centric, circular orifice, while the tubular section of the rotor extends likewise in the shape of a bell within the tubular section of the stator and concentrically to the bell shape of the stator: Its bell head likewise has a centric orifice which merges into a tubular boss, which penetrates into the orifice of the stator bell head, thereby forming means for receiving an antifriction bearing, and which by its outer periphery also supports the hub.

[0017] In a preferred embodiment the antifriction bearing is a tapered roller bearing with a double race.

[0018] For practical purposes the tubular section of the rotor is equipped with a brake bearing structure and with a locking brake on the end which faces the supporting frame.

[0019] Therefore, in this version the rear bearing was omitted and the front bearing was replaced with one single special bearing, such as a tapered roller bearing with a double race, which has a smaller diameter and is accommodated in a practical narrowed portion in the front part of the stator structure. This narrowed portion is realized by a reinforcing, sandwich-like toroidal element which only partially reduces the accessibility to the hub.

[0020] The use of one single tapered roller bearing with a double race offers the following advantages over the first variant, with two bearings, described above:

[0021] 1. simplification of technology for mounting the generator (one-sided accommodation of the bearing);

[0022] 2. elimination of hazardous eddy currents in the generator made possible through formation of temporary circuits building up between the stator wall, the rotor wall and roller bodies of the bearings disposed at the ends of the active portion (windings);

[0023] 3. simplification of the adjustment processes of the bearing (the tapered rollers must be pre-stressed; the version with two bearings at the ends of the generator therefore presents design problems with respect to the constructional tolerances and thermal deformations);

[0024] 4. One single system of seals and lubrication concentrated in the front region of the generator;

[0025] 5. The bearing typology used furthermore offers a high degree of rolling precision (elimination of play thanks to the pre-stressing) and a low rolling resistance (noticeable increase in generator productivity).

[0026] Additional features and details are contained in the claims and in the description of a power generator actuated by wind, in its preferred embodiments as illustrated in the accompanying drawings.

[0027]FIG. 1 shows a sectional view along a vertical axial plane of a power generator actuated by wind energy, in accordance with the invention;

[0028]FIG. 2 shows a variant in a sectional view like that of FIG. 1.

[0029] In FIG. 1 a wind power generator is generally indicated by the reference number 1. This generator is mounted by way of a hollow transition element 2 to the upper end of a tower not further illustrated. The wind power generator 1 comprises a stator 3 and a rotor 4. The rotor 4 is connected in a known manner to a hub 5, to which in the present case three hollow blades not shown here are connected. The blades are attached to flanges 6 of the hub 5. The rotor 4 is formed by a tubular section in the outer shell of which permanent magnets 7 are set. These magnets come to rest opposite windings 8 secured on the inner surface of a tubular section of the stator 3. One antifriction bearing 9 and 10 each is arranged in the region of the ends of the tubular section of the stator 3. These bearings rotataby support the tubular section of the rotor 4. Of the two antifriction bearings 9 and 10, at least one must be a thrust bearing. Both are arranged in such a manner that the permanent magnets 7 and the windings are held between them.

[0030] The hub 5 is attached by its flange 11 to one of the ends of the tubular section of the rotor 4. The flange is joined by threaded bolts 13 to an annular collar 12 of the tubular section 4.

[0031] On the side facing the hub 5 the tubular section of the rotor 4 has a depression 14 in its outer surface, which can receive the inner ring 15 of the antifriction bearing 9, while the outer ring 16 of the same pipe bearing can freely glide on the outer surface of the tubular section of the stator 3. In addition, the antifriction bearing 9 is held between the depression 14 and the angular ring element 17.

[0032] On the end facing away from the hub 5 the tubular section of the stator 3 is connected to a flange 19 of the transition element 2, which flange is joined by screws 21 to a thickened edge 20 in the tubular section of the stator 3. The outer ring 22 in the antifriction bearing 10 is held in position by a radial land 23 of the stator section 3 and by a spacer 18 directly abutting the flange 19, while the inner ring 24 of the same antifriction bearing 10 is received on a belt 25 recessed into the outer surface of the tubular section of the rotor 4. The inner ring 24 is further held in position by an angular element 26 with an L-shaped cross section.

[0033] In a first variant of FIG. 2 a wind power generator 100 comprises of a rotor 104 located on the outside of a stator 3. The rotor 4 is supported by the stator 3 in a manner similar to that described with reference to FIG. 1. In this case, the windings 108 are located on the outer surface of the stator 103, while the permanent magnets 107 are in the inner surface of the rotor 104. In the preferred embodiment according to FIG. 3, the wind power generator of the invention is indicated as a whole with the reference number 200. It is affixed to a frame 201 on the upper end of a tower 202 that is only partially shown. In this case as well, the wind power generator 200 has a stator formed by a tubular section 203, of which one end is fastened by a screw connection 204 to the frame 201.

[0034] On the outside, radial cooling ribs 204 extend from the tubular section 203, while stator windings 206 are accommodated on the inside. On the side facing away from the screw connection 204, the tubular section 203 ends in the manner of a bell with a torus-shaped, sandwich-like head 207. This bell head supports in its orifice an outer ring 208, which together with an inner ring 209 forms a tapered roller bearing 210 that projects out to support a tubular boss 211 of a toroidal bottom 212 of a tubular section 213, which lies concentrically to the tubular section 203 and carries permanent magnets 214 of the rotor on its outer surface. The magnets lie opposite the windings 206 of the stator.

[0035] The tubular section 211 is connected to a hub 216 by means of a screw connection 215 having a covering or hood 217.

[0036] On the side facing away from the tubular boss 211 the end of the tubular section 213 is oriented toward a brake supporting structure 218, which is capable of braking the tubular section 213 of the rotor, or rather the motion of the blades. 

1. A wind power current generator comprising a support (2), a stator (3), which is fixed to the support (2), a rotor (4) that can rotate in relation to the stator (3), a hub (5) connected to the rotor (4) and at least two blades radially extending away from the hub (5), characterized in that the stator (3) and the rotor (4) are formed by tubular sections that are concentric to one another, on whose respective, opposite surfaces permanent magnets (7) and windings (8) are placed, and which extend beyond the magnets and the windings in order to accommodate an antifriction bearing on at least one side.
 2. The generator according to claim 1, characterized in that one antifriction bearing (9, 10) is provided at each respective end of the tubular sections, with the permanent magnets and the windings lying between said bearings.
 3. The generator according to claim 1, characterized in that the stator is located on the inside relative to the rotor (4).
 4. The generator according to claim 1, characterized in that the stator (3) is located outside of the rotor (4).
 5. The generator according to claims 1 to 3, characterized in that the permanent magnets are located on the rotor.
 6. The generator according to the preceding claims, characterized in that at least one of the bearings is a thrust-type roller bearing.
 7. The generator according to the preceding claims, characterized in that the interior of the generator forms a passage from the interior of a supporting tower to the hub and inside the blades.
 8. The generator according to the preceding claims, characterized in that owing to the chimney effect the hollow structure encourages the supplying of warm air toward the blades, making possible an improved exploitation of the thermal losses produced by the various electrical and electronic installed components.
 9. The generator according to claim 1, characterized in that only one single antifriction bearing (210) is provided.
 10. The generator according to claim 1 and 9, characterized in that the antifriction bearing (219) is a tapered roller bearing.
 11. The generator according to claim 1, 9 and 10, characterized in that tubular section (203) of the stator extends bell-like in the direction of the hub (216), the head of said bell having a centric, circular orifice, while the tubular section (213) of the rotor within the tubular section (203) of the stator likewise extends in the shape of a bell concentrically to the bell shape of the stator, and its bell head likewise has a centric orifice merging into a tubular boss (211) which penetrates into the orifice of the bell head of the stator, thereby forming means for accommodating the antifriction bearing (211), and which by its outer periphery supports the hub (216).
 12. The generator according to claim 1, 9, 10 and 11, characterized in that the antifriction bearing is a tapered roller bearing with a double race.
 13. The generator according to claim 1, 9, 10 and 11, characterized in that on its end of which faces the supporting frame the tubular section (213) of the rotor is provided with a brake bearing structure and with a locking brake. 